<template>
<div class="xtx-carousel" @mouseenter="stop" @mouseleave="start">
    <ul class="carousel-body">
        <li class="carousel-item" v-for="(item, i) in sliders" :class="{ fade:index === i}">
            <RouterLink to="/">
                <img :src="item.imgUrl" alt="">
            </RouterLink>
        </li>
    </ul>
    <a @click="toggle(-1)" href="javascript:" class="carousel-btn prev">
        <i class="iconfont icon-angle-left"></i>
    </a>
    <a @click="toggle(1)" href="javascript:" class="carousel-btn next">
        <i class="iconfont icon-angle-right"></i>
    </a>
    <div class="carousel-indicator">
        <span v-for="(item, i) in sliders" :key="i" :class="{ active:index === i}"></span>
    </div>
</div>
</template>

<script setup>
import { ref, watch, onUnmounted } from 'vue'

const props = defineProps({
    sliders: {
        type: Array,
        default: () => []
    },
    duration: {
        type: Number,
        default: 3000
    },
    autoPlay: {
        type: Boolean,
        default: false
    }
})

// 默认显示的图片索引
const index = ref(0)

// 自动轮播
let timer = null
const autoPlay = () => {
    clearInterval(timer)
    timer = setInterval(() => {
        index.value++
        if (index.value >= props.sliders.length) {
            index.value = 0
        }
    },props.duration)
}

watch(() => props.sliders, (newVal) => {
    // 有数据&开启自动轮播，才调用自动播放图片
    if (newVal.length && props.autoPlay) {
        index.value = 0
        autoPlay()
    }
}, { immediate: true })

// 鼠标进入停止，移出开启自动，前提条件：autoPlay为true
const stop = () => {
    if (timer) clearInterval(timer)
}

const start = () => {
    if (props.sliders.length && props.autoPlay) {
        autoPlay()
    }
}

// 指示器切换，上一张，下一张
const toggle = (step) => {
    const newIndex = index.value + step
    // 判断是否为最后一张
    if (newIndex >= props.sliders.length) {
        return  index.value = 0
    }
    // 判断是否是第一张
    if (newIndex < 0) {
       return  index.value = props.sliders.length - 1
    }
    index.value = newIndex
}

// 组件销毁，清理定时器
onUnmounted(() => {
    clearInterval(timer)
})
</script>

<style scoped lang="less">
.xtx-carousel{
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .carousel{
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0,0,0,0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background:  #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0,0,0,.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev{
        left: 20px;
      }
      &.next{
        right: 20px;
      }
    }
  }
  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }
}
</style>